This is a divisional application of Ser. No. 308,749 filed Feb. 10, 1989. Airborne asbestos contamination in buildings is a significant environmental problem. Various diseases have been linked with industrial exposure to airborne asbestos, and the extensive use of asbestos products in buildings has raised concerns about exposure to asbestos in nonindustrial settings. Surveys conducted by the Environmental Protection Agency (EPA) estimate that asbestos-containing materials can be found in approximately 321,000 schools and 733,000 other public and commercial buildings in this country.
In an effort to avoid the hazards associated with exposure to airborne asbestos, abatement actions or procedures are being extensively conducted and the Environmental Protection Agency has published a booklet entitled "Guidance for Controlling Asbestos-Containing Materials in Buildings."
During the abatement action, one or more air filtration units, usually several air filtration units, are positioned throughout the work site to filter the air in the work place.
Each of the air filtration units include an air inlet or suction opening and an air discharge or outlet opening. The air inlet of the air filtration unit is in communication with the interior of the contaminated space so that the contaminated air is drawn into the filtration unit and then exhausted from the exhaust side of the filtration unit. The exhaust side of the air filtration unit is normally connected by means of a flexible conduit to a selectively closable air exhaust means such as an air box as disclosed in the patent application Ser. No. 179,864 filed Apr. 11, 1988 entitled "Means for Sampling the Exhaust Air of an Air Filtration Unit." In some installations, an air box is not utilized although some form of selectively closable exhaust opening is provided at the end of the flexible air conduit.
A problem of contamination occurs when an air filtration unit malfunctions and must be replaced. When the malfunctioning air filtration unit is disconnected from the air conduit connecting it to the air box, contaminated air enters the interior of the air conduit. Further, when a new air filtration unit is brought into the contaminated area, the exhaust side of the new air filtration unit becomes slightly contaminated itself. If the contaminated exhaust of the air filtration unit is connected to the contaminated air conduit, contaminated air will be discharged into the interior of the air box or the atmosphere when the air filtration unit is actuated.
A problem of contamination also occurs when the primary HEPA filter in a functioning air filtration unit must be replaced. When the dirty primary HEPA filter is removed from the air filtration unit, the downstream side of the unit may become contaminated by the air within the contaminated space. Further, when the new HEPA filter is brought into the contaminated space, the downstream side of the new filter may also become contaminated as it is placed into the air filtration unit.
It is therefore a principal object of the invention to provide a method and means for replacing a malfunctioning air filtration unit.
A further object of the invention is to provide a method and means for replacing a malfunctioning air filtration unit which prevents contamination of the air conduit and air box normally associated therewith.
Yet another object of the invention is to provide a method and means for replacing a malfunctioning air filtration unit through the use of a Y-shaped air box having at least three selectively closable openings.
It is yet another object of the invention to provide a method and means for replacing a primary HEPA filter in a functioning air filtration unit.
These and other objects of the invention will be apparent to those skilled in the art.